Effects of the Reynolds number and structural damping on vortex-induced vibrations of elastically-mounted rigid cylinder

摘要

In this work, analyses of the damping ratio and turbulence effects on three-dimensional vortex-induced vibrations of a two degrees-of-freedom elastically mounted rigid cylinder are carried out. Simulations are conducted for damping ratios of zeta = 0.5, 2.5, 5.0 and 10.0% for flows covering Reynolds numbers in the three TrSL flow regimes, in the range of Re = 7.5 x 10(2) to 1.3 x 10(5). Variation of the response amplitudes, phase angles, force coefficients and frequency ratios by the damping ratios and Reynolds number are investigated using the classically damped spring-mass system equations programmed inside the CFD software Fluent. New results are obtained for very high Reynolds numbers and different damping ratios. New conclusions are drawn from the mechanical responses using surface interpolation of 240 data-points, which allows the investigation of the trends of a given response variable xi based on the A(gamma)*vs.zeta((m* + C-A) vs. xi three-dimensional plot proposed by the authors. A new mechanism of elongation of the upper branch extension based on the universal reduced damping, S-u, during the TrSL3 regime is described.